Updating to correct Gaia as a requirement (#44)

Signed-off-by: Mary Anthony <mary@blockstack.com>

_develop/zero_to_dapp_1.md

@@ -118,10 +118,11 @@ companies that grew the cloud computing market.
 
 <ul>
 <li>Implement Blockstack authentication</li>
-<li>Store data in a Gaia storage hub</li>
 <li>Invite registration and use by the general public</li>
 </ul>
 
+<p>Storing data in a Gaia storage hub is optional. Potentially in the future it may be required.</p>
+
 <p>As you work through this Zero-to-DApp tutorial, you’ll build and deploy a sample
 application that meets these requirements. While the application you build won't
 be eligible for application mining, completing the tutorial makes you

_develop/zero_to_dapp_3.md

@@ -177,8 +177,8 @@ explorer</a> and search for your ID:
 <img src="images/explorer.png" alt="">
 
 <div class="uk-card uk-card-default uk-card-body">
-<h5>App Mining Requirement: Gaia Storage</h5>
+<h5>App Mining Optional: Gaia Storage</h5>
-<p>To participate in application mining your application must make use of Gaia storage.
+<p>Use of Gaia storage is not required for application mining. Keep in mind, using Gaia may make data storage easier as it is designed to work in the Blockstack Ecosystem.
 </p>
 </div>
 

_develop/zero_to_dapp_4.md

@@ -99,7 +99,7 @@ To add an app, do the following:
       </tr>
       <tr>
         <td><strong>Storage</strong></td>
-        <td>Choose Gaia.</td>
+        <td>Choose Gaia if you are using it.</td>
       </tr>
       <tr>
         <td><strong>Authentication</strong></td>